Thermostatic circuit-closer.



` T. BJFREAS. THERMOSTATIC CIRCUIT CLOSER. APPLICATION FILED APR.23.i914'.

l Pteted Dec. 3, 1918.

3 SHEETS-SHEET 2.

:Rouw M0552.

3 SHEETS--SHEET 3.

THOMAS B. FREAS, OF LEGNIA BOROUGH, NEVI JERSEY, ASSGNGR TO V. W'EBER etClvIPilqY, OF CHICAGO, ILLNOS, il. CORPOPJTIG-I GF ELL'QATG TlERdGSTATCCBC'U'LT-CLOSER.

To all fw from t may ccf/were Be it knoivn 'that l, THOMAS Funes, af

citizen or" the United States of America, and a resident of the boroughot Leonia, county of Bergen, and State of New Jersey, have inventedcertain new and useful improvements in Thermostatic Circuit-Closers, oitwhich the following is a specification.

This invention is a division of my application Serial lo, 75l-,717, ledMarch 17, 1918, and relates to thermostatic circuit closers of a kindsuch as is adapted for use in connection with constant temperature bathsor the type designed Jfor use as chemical laboratory ovens,bacteriological incubators and other similar or analogous apparatuswhere such device finds application and the obiect of the invent-ion isto provide means quickly and accurately esponsive to changes intemperature and for maintaining; the temperature accurately at anydesired degree of heat irrespective ot the changes orp room temperature.This invention is turtherniore designed in part as an improvement uponthe type of apparatus heretofore patented by me in U. S. Letters`@attent No. 1,024,565, dated April 30, i912.

ln the following have described, in connection with the accompanying;drawings, a structure illustrating the application or' the principles ofmy invention, the features thereof being more particularly pointed outhereinafter in the claims.

ln the drawings Figure l is central vertical sectional vievv or' oneform of'constanttemperature bath illustrating the practice of theprinciples of my invention, certain parts being shown in elevation.Fig'. 2 is a detail vieiv of the loiver part of the thermostaticcont-rol. isanisornetric perspec tive view, on a Somewhat enlargedscale, of the automatic switch mechanism and control devices inconnection therewith and Fig. el is a diagran'nnatic View of theelectrical connections and Wiring system.

Similar numerals ot rete ence indicate similar parts throughout theseveral vieivs.

ln the form selected to illustrate the invention, as shown in thedrawings, the casing comprises an outer bof; l0 and an inner box il, thelatter forming a receiving` chamber l2 wherein the objects to he actedupon Specication of letters Patent.

Serial lo. 833,860.

are to be placed. rlhe Walls of the outer box are shown as extendedupwardly to form, in connection with the top lOa and the tloor 16, achamber` l5 for the reception of the automatic switch mechanism andassociated parts hereinafter described.

37 is an opening through cover 10al for the purpose hereinafterdescribed. 3S, 38 arel ventilatingtubes leading, from the chamber l2through cover lOl to the exterior and through which thermometers may besuspended.

Referring noiv to l and 3, reference numeral 39 indicates a bed platesecured to 'floor l@ and carrying' lugs 4G, i0, bearings 40, l0" andstandards Lil, il and 42, @l2 preferably cast therewith. Standards s2,42 are provided with Ways i3 for guiding the vertically adjustable scaleface di. Scale face -l carries an interiorly screw threaded lug; orblock e5, through which passes a 'threaded rod 4:6 rotatably mountedagainst vertical movement in standard rlhe top ot rod sib is providedwith a slot so that, by means of a screw driver inserted through opening37, the rod may be rotated to cause lugA or block and its attached scaleface di, to tra-vel vertically, 43a is a 'support mounted on standard 42to form a guide for the upper end oi? rod e6.

The rear standards el, Lil, support the bearings for the controllinglevers 47 and 48. The lever 8 is shown as' broken in Fig. 3 for thesalte ot clearness. yoke carrying` lever 47 and is pivoted at 50 instandards 4l. Tl e tree end of lever i7 projects through slot 54 inscale 'face '-l; and carries a contacter point 5l and a pointer 52adapted to indicate on the temperature scale on scale face The divisionsoi' scale 53 may represent an 'arbitrary calibra- 49 is a' the bedplate. 63 is a female threaded block engaging male threaded rod 64mounted to rotate in bearings 40a and 40h on bed plate 39 and securedagainst longitudinal movement by means ot' a collar Block 63 carries adepending finger 66 which travels in a slot 67 in the bed plate 39 toprevent the block 63 from turning. A link 68 connects the block 63 andthe lifting arm 60 as shown. The' `t'ree end oi' the rod 64 projectsthrough the front wall of the casing and` through the scale face 44 asshown and is provided withan operating knob 69 so that the rod 64 may bcrotated from without by the operator. v

Lever 48 is secured at one end to an arm 70l on a rocker plate 70 but isinsulated therefrom by means otl suitable insulation 71. Rocker arm 70is pivoted at 50, 50 to standards 4l, 41. At 72 lever 48 is offset sothat the tree end of the lever may extend through slot 54 in scale t'ace44 above the free end of lever 47. Lever 48 carries a contactor 73adapted to contact with contactor 51 on lever 47. Rocker plate 70 isprovided with an offset lug 701 having a concave` shaped bearing (notshown) on its under side adapted to engage the upper end of a pin 74rigidly carried by plate or bar 75. The lug 70b is offsetwith relationto the center of rotation oflever 48 about pivots 50, so that anyvertical movement of pin 74 will cause lever 48 to rock and causecontactor 73 to move vertically a distance, which distance compared withthe vertical Ymovement of pin 74, is according to the ratio of thedistances of contacter 73 and pin 74 from the center of rotation 50. Theplate or bar 75 is so adjusted, by the means hereinafteidescribed, thatpin 74 willengage the concave shaped bearing in lug 7()b when theten'iperature of thermostatic tubes 76 corers 52 on scale 53.

The thermostatic device comprises in part' the thermostatic tubes 76,76, made= of a' material adapted to expand and contract in response tovariations in temperature, prefera-bly of thin brass and perforated: Thetubes 76 are preferably perforated to provide for a freer circulation ofair in order to canse a quicker response to changes in ten'ipcrature.The material of which tubes 7 (i are made is such that the highestco-eiicient of expansion may be obtained consistent with strength andpermanency of form under varying conditions of temperature. Brass hasbeen found to give good results,A I

The upper ends of tubes 76 are rigidly fastened to bar and the lowerends of tubes 76 are connected with bar 77 by means of adjusting screws78, 78. By means of these adjusting screws 78, 78, bar 75 carried bytubes 76, 76 may be vertically adjusted indicated on the scale. 53.

and thereby'through pin 74, lug 70b and le-K ver arm 48, adjustcontactor 73` so that it may come within range of scale 53, the neradjustment being made by the vertical movement ot the scale face 44 ashereinbefore described.

79 indicates a rod made of material whose coeicient of expansion ispractically m7.'

connected across the mains and controlled by a switch 88. Lamp 35 isconnected across the mains and controlled' by a two-way switch 89 sothat lamp 35 may be connected on'the one hand, through contacts 82 and83, directly across the mains or, on the other hand, may be connectedacross the-mains vthrough contacts 82 and 84, wire 94, conductor 91,contactors'l and 73, lever 48 and conductor 93. i

' lVire 86 is connected to .heating elements 32 and 33 through switch90. Primary heating element 32 is connected by means of conductor 91 tolever arm 47 which latter is divided electrically into two parts byinsulator 81. From lever arm 47 the path ofthe current is throughcontactors 51 and 73,'- lever arm 48' and conductor 93 to main 85.Secondary heating element 33 is connected by means ot conductor 92,Vconducting standard 58, contactors 57 and 56 and wire 97 to conductor 91and thence by the path hereinbefore described in connection with primaryheatingelement 32.

Contactors 51 and 73 are protected, on breakingthe circuit by condenser95 and contactors 56 and 57 are similarly protected by condenser 96.'When contactors 56 and 57 are closed, and the additional load of heatingelement 33 is on contactors 51 and 73, these latter contactors, on thebreaking of the circuit, are protected by condenser' 96 irl-,addition t0condenser 95.

In the operation of the apparatus described, the operator after closingswitch 90, by means of operating knob 69 sets the pointers 52 at thedesired temperature as setting, contactor 73 will rest` on contacter 51,thereby completing the electrical connec- Asfsuming that tion throughprimary heating element rlhe heat given off from element 32 circulatingthrough chamber 12, freely by convection'currents or forcibly by theJforced draft or' the blower 26, will raise the temperature et thethermostatie tubes 76, 7 6, which tubes will expand and, because ot' thenon-expansion of rod 79, will cause bar 7 5 to rise and hence raiselever arm e8 and, on

7 sutlicient expansion of thermostatic tubes 7G,

'of the chamber l2, which is continuously being lost by conductionthrough the Walls even though these latter be et the best possibleinsulation, will be intermittently replaced by means of heating element32 operating as hereinbefore described.

The capacity of heating element 32, for the more or less lowtemperatures, should be as low as possible consistent with the amount otheat-required, because, for accurate regulation, the quantity otl heatthrown in intermittently should have a low ratio to the quantity of heatlost continuously through the Walls, otherwise a comparatively.- large-quantity `ot intermittent heat throuinin would cause a comparativelylarge ilu'ctnation ot the temperature ot cham ber v"12. v t

Noia ivhen it is desired to operate at higher temperatures,- additionalheat is neeessary. j. 'Therefoie, when the operator sets the pointers552 at a more or less high temperature, lever-t7 will carry contacterinto Contact with contacter 57, thereby throwing secondaryv heatingelement 33 into direct connection With conductor 91 and thus parallelwith heating elemcnt.

lt will be observed that levers 47 and 4S rotate 'on a common center 50,50. This method of construction causes the eontacting surfaces ofcontacter-s 51 and 78 to be always in parallel'and thus in goodelectrical Contact, regardless of their position on the scale.

The method herein described ot' adjusting the therniostatic control andof permitting the operator to'set the temperature of the chamber l2 atany desired predetermined point as'indicated to him by pointers 52 onscale 53, is a very important point in thermostatic construction.

Y lt is obvious that additional heating` elements similar to element 33may be provided without departing from the spirit of the invention, itbeing understood that the contactors 56 and 57 may be adjusted to suitany required inflow ot' heat to assist the primary heatingelement.

.l do not restrict myself to the use el my invention in connection withconstant temperature baths as it is obvious that the invention finds usein any suitable thermostatically controlled circuits or mechanism, nordo l restrict myself to any ot the details ot construction, arrangementof parts or composition o't' material as shown or described further thanthe scope of the appent ed claims demands.

That l claim and desire to secure by Letters Patent is:

l. n apparatus of the class described, a pair ot' independentlycontrollable lever arms mounted on a common center, a contacter carriedby each ot said lever arms adapted to malte contact vertically with eachother, means for positively controlling the movement ot one of said levr arms and its contacter' and means for thermostatically controllinglthe movement of the other of said lever arms and its contacter. 't

2. In apparatus of the class described. aY

pair of contactors vertically movable relative to each @the and meansfor controlling said movement including a rocker arm in operativerelationship to one et said contact'ors, a pin for actuating said rocherarm, a supportI for said pin, a rod having a comparatively highcoetlicient of expansion tastened to said support and means permittingthe expansion and contraction said rod to actuate said pin.

3. ln apparatus of the class des-wibed, a pair of eontactors verticallymoi, le relative to each other, a lever arm in operative relationship toone of said contactors and s means for actuating said lever armincluding a thermostat comprisinga plurality ot rods having acomparatively high coefficient of expansion, a rod havinga i gible coemcient or expansion, a bar cai-ind by one end of said lirst mentionedrods, a bar carriedby the other ends of said rods and one end of saidlast mentioned rod and a tiXed support for the other end of said lastmenf tioned rod.

Il. ln apparatus of the class described.v a pair. of contacter-svertically movable relative to each other, a lever arm in operativerelationship to one of said contacter-s and means for actuating saidlever arm including a thermostat comprising a plurality oi' rods havinga comparatively high coethcient ot expansion, a rod having a negligiblecoetlicient ot expansion, a bar to which the ends ot' said 4firstmentioned rods are rigidly secured, a bar to which the other ends ofsaid rods are adjustably secured and to which one end of said lastmentioned rod is also secured and a tiXed support` for 'the other end ofsaid last mentioned bar.

5. In apparatus of the dass described, a In testimony whereof I havesigned this pair of lever arms, supports for one end specification inthe presence of two subscrbl0 thereof and contactors at the other ending Witnesses. thereof, a. yoke on one of said lever arms y pivoted insaid supports, and a plate, to THOMAS B" which the other lever arm isattached, piv- Wltnesses: oled to said supports Within said yoke and K.G. LE ARD,

on a common center of rotation therewith. S. M. BALDER.V

